Expert Guide Editorially reviewed

The Best Email Security Tools in 2026

Email is still where most breaches start. These are the platforms that actually catch business email compromise, not just the spam your gateway already blocks.

Louis CorneloupFounder, Dupple · 810,000+ readers · Updated Jul 2026

Independently researched. No pay-for-placement. 5 tools compared

TL;DR

The best email security tools in 2026 are Abnormal Security for stopping business email compromise on cloud mailboxes, Proofpoint for large enterprises that want the deepest threat intelligence, Microsoft Defender for Office 365 for the best value if you already pay for E5, Mimecast for teams that also need archiving and continuity, and Barracuda for smaller shops and MSPs. Your deployment model, gateway or API, matters as much as the detection engine.

More than nine in ten attacks arrive by email, and the ones that hurt are rarely malware. They are a convincing message from a spoofed CFO asking for a wire transfer, or a hijacked vendor account sending a fake invoice.

Legacy filters catch spam and known-bad attachments and miss exactly this. We looked at how each platform detects impersonation and account takeover, how it deploys, and what it really costs once you count the modules a security team needs. Here are the five worth a bake-off.

Top Picks

Based on features, real-world fit, and value for money.

Best Email Security Tools in 2026: 5 tools compared, updated Jul 2026
Tool	Pricing	Best for
Abnormal Security	Custom / contact sales	Microsoft 365 and Google Workspace shops fighting BEC
Proofpoint	Custom / contact sales	Large enterprises that want the deepest threat intelligence
Microsoft Defender for Office 365	From about $2/user/mo (Plan 1), or bundled in Microsoft 365 E5	Microsoft 365 organizations already holding E5
Mimecast	Custom / contact sales	Teams that want security, archiving, and continuity in one contract
Barracuda Email Protection	From about $6/user/mo	Small and mid-size teams and MSPs that want simple setup

Pricing read from each vendor's own published pricing page, checked Jul 2026. Every vendor here publishes a price.

Abnormal Security

Top Pick

Best for: Microsoft 365 and Google Workspace shops fighting BEC

PricingCustom / contact sales

+Best-in-class business email compromise and account-takeover detection

+API deployment in minutes, no MX or mail-flow change

+Auto-remediates malicious mail already in the inbox

−Cloud mailboxes only, no on-prem Exchange

−Public pricing is quote-only

Visit Abnormal Security →

Proofpoint

Best for: Large enterprises that want the deepest threat intelligence

PricingCustom / contact sales

+Strong detection backed by wide threat visibility

+Deep controls for DLP, encryption, and compliance

+Proven at very large scale

−Heavy to configure and administer

−Priced and built for the enterprise, not small teams

Visit Proofpoint →

Microsoft Defender for Office 365

Best for: Microsoft 365 organizations already holding E5

PricingFrom about $2/user/mo (Plan 1), or bundled in Microsoft 365 E5

+Excellent value, effectively free with E5

+Deep native integration with Microsoft 365

+Safe Links and Safe Attachments cover the basics well

−Weaker against advanced BEC than dedicated tools

−Best experience only inside Microsoft 365

Visit Microsoft Defender for Office 365 →

Mimecast

Best for: Teams that want security, archiving, and continuity in one contract

PricingCustom / contact sales

+Security, archiving, and continuity in a single platform

+Keeps email running during a Microsoft 365 outage

+Mature admin controls and reporting

−Gateway model means an MX change and more setup

−Console feels dated next to API-native rivals

Visit Mimecast →

Barracuda Email Protection

Best for: Small and mid-size teams and MSPs that want simple setup

PricingFrom about $6/user/mo

+Simple to deploy and manage

+Good value for smaller organizations

+MSP-friendly multi-tenant management

−Detection depth trails the enterprise leaders

−Advanced features are split across separate SKUs

Visit Barracuda Email Protection →

What it is

An email security tool inspects inbound, outbound, and often internal mail to block phishing, malware, business email compromise, and data leaks before they reach a user or leave your organization. Older products are secure email gateways that reroute your MX record and scan mail in transit.

Newer ones connect through the Microsoft 365 or Google Workspace API, read signals the gateway never sees, and pull malicious messages back out of the inbox after delivery.

Why it matters

Attackers moved past malware because identity is easier. A payment-fraud email carries no attachment and no link for a scanner to flag, so it sails through a signature-based filter and lands in front of a busy employee.

The average wire-fraud loss runs into six figures, and one compromised internal account can phish your whole company from a trusted address. Email is the single most attacked channel, which makes the layer that watches it one of the highest-return controls most teams own.

Key features to look for

Phishing and BEC detectionEssential

Behavioral analysis that flags impersonation, payment fraud, and social-engineering messages that carry no malware and slip past signature-based filters.

Malware and malicious URL defenseEssential

Attachment sandboxing plus link rewriting and time-of-click scanning, so a URL that turns malicious after delivery is still caught.

Account takeover detectionEssential

Spots a compromised internal mailbox sending lateral phishing from a trusted address, which external-only filters never see.

Deployment model

Gateway products reroute your MX record; API-based products connect to Microsoft 365 or Google Workspace with no mail-flow change and faster rollout.

Automated remediation

One-click or automatic pull of malicious mail already delivered to inboxes, plus an abuse mailbox and a user-report button that feeds triage.

Data loss prevention and encryption

Outbound controls that stop sensitive data leaving by email and enforce encryption on regulated content.

Mistakes to avoid

×Assuming your Microsoft 365 or Google filter is enough. Native filtering catches spam and known malware but misses the payment-fraud and impersonation emails that cause the biggest losses.

×Buying on malware-catch rates alone. The threats that matter now carry no payload, so test each tool against real business email compromise samples, not signature detection.

×Ignoring outbound and internal mail. A hijacked internal account phishing your staff from a trusted address is invisible to a tool that only inspects inbound traffic.

Expert tips

→Run a two-to-four week evaluation on live mail before you switch. API-based tools sit alongside your existing filter and show exactly what they would have caught.

→Turn on the user-report button and route it into automated remediation, so a single report can pull the same malicious message from every inbox.

→Layer, do not just replace. Microsoft or Google handles bulk spam cheaply, and a dedicated tool adds the BEC and account-takeover detection they lack.

The bottom line

If your mailboxes live in Microsoft 365 or Google Workspace and business email compromise is your real worry, start with Abnormal Security, its behavioral model catches what gateways miss and deploys in minutes.

Large enterprises that want the deepest intelligence and tightest compliance controls should look at Proofpoint. If you already pay for E5, Microsoft Defender for Office 365 is the value pick, and Mimecast earns its place when you also need archiving and continuity.

Smaller teams and MSPs are well served by Barracuda. Test any of them against live mail before you commit.

Frequently asked questions

What is the difference between a secure email gateway and an API-based tool?

A gateway reroutes your MX record and scans mail before it reaches the mailbox, which means an MX change and more setup. An API tool connects directly to Microsoft 365 or Google Workspace, deploys without touching mail flow, and can see internal messages and pull malicious mail back after delivery.

Do I still need email security if I use Microsoft 365?

Yes for most teams. Microsoft's built-in filtering handles spam and known malware well, but dedicated tools are stronger against business email compromise, impersonation, and account takeover, which are the attacks that cause the largest financial losses.

What is business email compromise?

Business email compromise is a fraud where an attacker impersonates an executive, vendor, or colleague to trick someone into wiring money or sharing data. These emails usually carry no malware or links, so they defeat signature-based filters and need behavioral detection to catch.

Can one tool replace my whole email stack?

Often, but many teams layer. Microsoft or Google handles bulk spam cheaply, and a dedicated platform adds the advanced phishing, BEC, and remediation those native filters lack. Test on live traffic to see what each one actually catches for you.

Get the Cyberpresso brief

Free daily newsletter, read in 5 minutes.

Subscribe free